class Solution {
public:
    int subarraySum(vector<int>& nums, int k) {
		unordered_map<int,int> hash;
		hash[0]=1;
		
		int sum=0,ret=0;
		for(auto x:nums)
		{
			sum+=x;
			if(hash.count(sum-k))ret+=hash[sum-k];
			hash[sum]++;
		} 
		return ret;
    }
};
